<!DOCTYPE html>
<html>
  <head>
    <style>
      body > div { color: green; }
      .toremove { color: red; }
    </style>
  </head>
  <body>
    <div class="toremove">
      This should be green
    </div>
    <script>
      document.body.firstElementChild.classList.remove("toremove");
    </script>
  </body>
</html>
